Transition piece for connecting an upper tower section to a lower tower section by means of connection profiles

ABSTRACT

The invention relates to a transition piece for connecting an upper tower portion with connection profiles of a lower tower portion. The invention further comprises the respective connection profiles. The transition piece is particularly suitable for a hybrid tower, e.g. for a wind turbine, wherein the upper tower portion is configured, for example, as a steel tubular tower and the lower tower portion as, for example, a lattice tower structure.

The application relates to a transition piece for connecting an upper tower portion with lower tower portion by means of connection profiles. The application further comprises the respective connection profiles. The transition piece is particularly suitable for a hybrid tower, e.g. for a wind turbine, wherein the upper tower portion is configured, for example, as a steel tubular tower and the lower tower portion as, for example, a lattice tower structure.

Towers for onshore wind turbines are typically embodied as tubular towers, in particular steel tubular towers. This design, also referred to as a shell construction, has the advantage that the tubular towers consist of individual segments so that the individual tower components are transportable. Transportability is a limiting factor in particular with regard to tower diameters of tall towers, since with hub heights of more than 120 m, a lower diameter of the tubular tower would exceed 4.5 m. Diameters of more than 4.5 m, however, are transportable on roads only with great difficulty, since bridges above roads and motorways often have a corresponding maximum clearance height. Onshore steel tubular towers are, without additional technical measures (e.g. additional longitudinal separation of the individual segments), thus limited to a hub height of approx. 120 m.

Hybrid tower designs, e.g. steel hybrid towers and prestressed concrete hybrid towers, are moreover known from the prior art. Steel hybrid towers have a lattice mast and a steel tubular tower. Prestressed concrete hybrid towers have a prestressed concrete tower section and a steel tubular tower section. Steel hybrid towers have the advantage that the lower tower portions, which usually have larger diameters, are made of comparatively convenient individual parts that may be assembled together and form a lattice supporting structure, and the upper tower portions are formed as a steel tubular tower. This design, however, requires technically complex solutions for a transition between the lower, lattice-like structure and the upper, tubular structure. To date, primarily only transition pieces that have a high material requirement and a complex or overdimensioned structure are known, which in particular are costly or are only transportable with relative difficulty.

EP 2 647 764 A1 for example describes a transition piece for connecting a tower with a lattice-like foundation structure in the offshore area. Here, the transition piece comprises a cylinder, wherein the cylinder has a flange at its upper end to support the tower base and is provided, on its lateral surface, with metal box sheets to pass the external forces into the foundation structure consisting of main struts and cross struts.

DE 10 2013 221 681 A1 describes a further example for a transition piece for a hybrid tower of a wind turbine. The transition piece comprises an adapter shell and multiple adapter plates, wherein in the adapter shell is configured to be tubular and the adapter shell and the adapter plates are connected to each other in a manner such that the adapter plates and the adapter shell partially overlap in the longitudinal direction of the tower. The fastening means may for example be screws, rivets, or collar pins, however advantageously screws are used, as these are releasable for maintenance of the transition piece and/or the tower. In particular in DE 10 2013 221 681 A1, it is clear that due to a small part size of the support elements used, a plurality of fastening means is necessary in order to enable a reliable force flow from the upper tower portion into the lower tower portion.

In view of the prior art, the object of the invention is to propose an alternative transition piece as well as connection profiles which enable a reliable force flow from an upper tower portion to a lower tower portion, and which at the same time are comparatively economical.

This object is achieved by a transition piece according to claim 1 and by connection profiles according to the independent claim. Advantageous embodiments and developments of the invention are described in the dependent claims.

The transition piece is connectable to an upper, tubular tower portion and to connection profiles. The connection profiles are, in turn, connectable to a lower tower portion which is preferably configured as a lattice structure. In order to connect the transition piece to the upper tower portion, the transition piece comprises an upper connection element. The upper connection element is formed in this case for example as a flange, preferably as a ring flange.

The transition piece further has a hollow structure which tapers towards the bottom. A lateral extent of the transition piece, i.e. an extent that is orthogonal to the longitudinal axis of the transition piece, decreases from the top toward the bottom.

The hollow structure may have a lower polygonal base area. The lower base area may also be configured to be round. The hollow structure may further have a round upper base area or polygonal upper base area. In a hollow structure with a polygonal upper base area, the number of corners of the lower polygonal base area is preferably lower than the number of corners of the polygonal upper base area. In a further exemplary embodiment, the hollow structure may be configured to be in the form of a frustum of a cone and have an upper and a lower base area, each configured to be round.

The polygonal or round base areas described in this application are typically arranged rotationally symmetrically about a tower longitudinal axis or a transition piece longitudinal axis.

The hollow structure may have an inner lateral surface. The inner lateral surface may, for example widen from the top towards the bottom. The inner lateral surface may for example be made of one or more several inner sheets, while the outer surface of the hollow structure may be made of outer sheets. This allows, for example, for a shell structure. It may also be provided for the hollow structure to comprise only one layer, i.e. the hollow structure may be configured as a single-layer shell. The outer lateral surface may then, for example, describe an outer side of a component forming the single shell, e.g. a sheet, and the inner lateral surface may describe the inner side of the component forming the single shell, e.g. the sheet. An outer side of this shell may have the same form as an inner surface of this shell. It may, however, also be provided that the shell is shaped such that an inner face has a different form than an outer surface of the shell. This may, for example, be realized by components cast as a shell.

The inner lateral surface may for example be configured in the form of a frustum of a cone such that the transition piece has an inner lateral surface widening toward the top in the form of a frustum of a cone. An upper base area is typically configured to be circular and a lower base area is also configured to be circular. A diameter of the lower base area is typically smaller than a diameter of the upper base area so that the inner lateral surface widens from the bottom toward the top. A lateral surface configured in this way may be advantageous in avoiding stress peaks on corners and edges and to thus optimize a force flow.

The frustoconical inner lateral surface, accordingly, may be an inner lateral surface of a hollow cone frustum, which at least in some regions may have an outer lateral surface in the form of a frustum of a cone. The hollow cone frustum may form a supporting structure of the transition piece. The upper tower portion, as is usual for steel tubular towers, preferably has a ring flange. The frustoconical inner lateral surface of the transition piece is typically arranged rotationally symmetrically about a hollow structure longitudinal axis. In one exemplary embodiment, in which the hollow structure has a frustoconical inner lateral surface, the hollow structure longitudinal axis may correspond in particular to a cone frustrum longitudinal axis of the frustoconical inner lateral surface.

The inner lateral surface may alternatively have a round upper base area and a polygonal lower base area. The transition from a polygonal lower base area up to the round base area may be smooth, such that the inner lateral surface may be configured to be substantially curved. The inner lateral surface may, however, also comprise edges and steps. Thus, a transition from the polygonal lower base area to the round upper base area may be realized in a more economical manner, e.g. by means of sheets adjoining one another.

The lower polygonal base area of the inner lateral surface or the hollow structure, or of the outer lateral surface, may for example be configured to be a triangle, a rectangle, a pentagon or a hexagon. The round upper base area of the inner lateral surface or the hollow structure, or of the outer lateral surface, may for example be configured to be circular or elliptical.

The base areas may be at least partially or entirely configured to be through-openings or be closed, for example by a sheet.

It may also be provided that the lower as well as the upper base area are configured to be polygonal. In this case, the polygonal upper base area typically has a higher number or corners than the polygonal lower base area. Thus, the polygonal upper base area may better approach a round shape of the upper tower portion.

The polygonal upper base area has, for example, at least five corners, preferably at least eight corners, particularly preferably at least twelve corners.

The hollow structure may have an exterior form that widens towards the top. The hollow structure may then, for example, have an outer lateral surface widening toward the top in the form of a frustum of a cone. The outer lateral surface may be also configured such that a lower base area is polygonal and an upper base area is round or also polygonal. The upper or lower base area of the outer lateral surface may then have the form of the upper or lower base area of the inner lateral surface. Die outer lateral surface of the transition piece may enclose an angle of at least 15°, preferably an angle of at least 20°, with the longitudinal axis of the outer lateral surface. This angle between the outer lateral surface and the longitudinal axis of the outer lateral surface may, for example, enclose at the most 45°, preferably at the most 60°.

The transition piece may further have at least one outer connection face for connecting the transition piece to the support members.

The at least one connection face is typically arranged at an outer side of the hollow structure and below the upper connection element.

The connection face may, for example, be configured to be a ring flange on the outer side of the transition piece. Moreover, connection face of various configurations may be provided. In an exemplary embodiment of the transition piece, the transition piece may have at least three outer connection faces which may be arranged on an outer side of the transition piece substantially rotationally symmetrically about the hollow structure longitudinal axis. The transition piece preferably has a plurality of collars which protrude on the outer side of the transition piece. The collar may have a closed form and for example may form a flange in the form of a frame. The connection face then forms a surface of the collar or flange. The collars are preferably formed integrally with the transition piece. The outer connection faces are consequently part of the transition piece. At each the outer connection faces, the transition piece is connectable to a connection profile which is connectable to the lower tower portion. To this end, the connection profiles, for example, may have a flange, the form of which corresponds to the form of the collar, in particular to the connection faces. A surface of the flange of the connection profile may be placed against the connection face and may be connected thereto, for example by means of welded connections or screw connections. The connection profiles may also have a frame-like flange on an upper side, the form of said flange corresponding to the collar of the transition piece so that the frame-like flange of the connection profile is insertable, for example interlockingly, into the collar of the transition piece. Additionally or alternatively, an integrally bonded connection may be provided. In addition, or alternatively, plug-in connections, screw connections, snap-action connections, adhesively bonded connections, or welded connections may be used. The connection profiles may also be connectable to the transition piece by means of shear cleats. In this case, the frame-like flange may form the shear cleat.

The upper tubular tower portion may be formed for example as a steel tubular tower, in particular as a supporting structure in the form of a shell. The transition piece may be formed at least in part as a supporting structure in the form of a shell. The transition piece is typically formed predominantly as a supporting structure in the form of a shell. The transition piece may be a symbiosis (or advantageous fusion/combination) of supporting structure in the form of a shell and supporting structure formed of rods.

Die frustoconical inner lateral surface of the transition piece may enclose an angle of at least 15°, preferably at least 24°, with the hollow structure longitudinal axis. This angle between the frustoconical lateral surface and the hollow structure longitudinal axis may, for example, enclose at the most 45°, preferably at the most 60°.

The transition piece may have an inspection opening. Installation and maintenance staff may thus enter inside the transition piece. An inspection opening may be provided for example on an underside of the transition piece. For example, a circular base area of the cone frustum may have a recess, which may serve as an inspection opening. A radius of a circular inspection opening may be designed in accordance with Rule 113-004 of the DGUV (German Social Accident Insurance Association), Annex 7, “Minimum Requirements for Access with Fall Arrest Personal Protective Equipment”. A radius is preferably at least 300 mm. Inspection openings may also be provided in the connection profiles and/or in the frustoconical lateral surface. Each of the connection profiles may have an inspection opening. Connection regions, for example screw flanges, between the transition piece and the connection profiles may thus be accessible for installation and maintenance staff.

The connection faces may protrude on the outer side of the transition piece. A plurality of collars may protrude from the outer side of the transition piece, and the collars may form at least three, preferably closed, protruding flanges in the form of a frame. The flanges may fully or partially frame a corresponding region of the outer side of the transition piece. The flanges, in a plan view, may have different forms, and for example may have a triangular, rectangular, square, circular, elliptical or polygonal form, or also a combination of these forms. A surface of these collars or frame-like flanges may form the corresponding connection face. The form of the connection face, as described above, preferably corresponds to a connection face of the connection profiles. The connection profiles may be connected to the transition piece at the connection faces for example by flange connections, shear cleats and/or by welded connections.

The outer side of the transition piece has typically elongate shapings between the connection faces. The shapings preferably extend from an upper side of the transition piece to an underside of the transition piece. The curvature of the embodiments is preferably continuous and in particular does not have any edges. Stress peaks in the transition piece may thus be avoided. The shaping, also referred to as a recess, may have a constant recess radius of curvature over the height of the transition piece. It is also possible that the radius of curvature of the shaping changes over the height of the transition piece. The radius of curvature is defined here as the radius of what is known as a circle of curvature, which best approximates the form of the shaping in a cross-section transverse to the longitudinal axis. The radius of curvature may be at least 0.2 m. The radius of curvature may also be at least 0.5 m. The radius of curvature is typically at most 1 m. The radius of curvature is preferably 0.5 m.

The transition piece may be formed integrally. For example, this may have the advantage that stability is increased and the installation effort is reduced. Nevertheless, the transition piece may also be separable. In such a case, the individual parts preferably may be screwed together or welded together. Interlocking connections for connection of the individual parts are also conceivable. Multi-part transition pieces may have the advantage that maximum dimensions are not limited by transport conditions, as already explained above.

The transition piece is suitable for towers that are used onshore and/or offshore. In an onshore application, the transition piece, along a longitudinal axis, preferably along the cone frustum axis, typically has a height of at least 2.5 m, preferably of at least 3 m. The transition piece may also have a maximum height along the longitudinal axis of 4.7 m, preferably of 4 m. This has the advantage that the transition piece, when already assembled or in a one-piece embodiment, is transportable relatively easily and may be transported on roads and under bridges overland. In an offshore application the height may be much greater, for example up to 7 m.

In one specific embodiment, the transition piece may have a total height along a longitudinal axis which corresponds to at least 50% of a diameter of the upper tower portion. The diameter of the upper tower portion is usually the diameter of the upper tower portion at a lower edge of the upper tower portion (without ring flanges). The total height of the transition piece may preferably correspond to at least 80% of the diameter of the upper tower portion. The total height of the transition piece typically corresponds to at most 150% of the diameter of the upper tower portion. Maximum transport dimensions may thus be observed, and at the same time stress peaks in the transition piece and/or in a tower comprising the transition piece are avoided. The transition piece may have much larger dimensions, particularly in offshore applications.

For improved transportability overland, the transition piece may typically have, perpendicularly to the longitudinal axis, a lateral extent of at least 3.5 m, preferably at least 4 m, and/or at most 5.5 m, preferably at most 4.5 m. The greatest lateral extent is usually on an upper side facing the tubular tower portion. The transition piece has its smallest lateral extent typically on an underside which faces the lower, lattice-like tower portion. The transition piece may have much greater lateral extents, particularly in offshore applications.

The transition piece may also have a lateral extent perpendicularly to the longitudinal axis, which in each position along the height of the transition piece corresponds to at least 0% of the diameter of the upper tower portion, in the region of the connection element to the upper tower portion preferably at least 105% of the diameter of the upper tower portion. The maximum lateral extent perpendicular to the longitudinal axis is typically, in each position along the height of the transition piece, at most 120% of the diameter of the upper tower portion. The diameter of the upper tower portion is usually the diameter of the upper tower portion at a lower edge of the upper tower portion. A good transportability overland may thus be achieved, in particular also on roads that have a clear width of only 5.5 m.

The present invention further comprises a connection profile to connect a transition piece, preferably a transition piece according to specifications mentioned above, with a lower tower portion. The connection profile may have an upper flange, the surface of which corresponds to the connection faces of the transition piece in such a way that the connection profile may be flange-mounted at an upper edge to the transition piece at the connection faces. The connection profile may also have a lower connection element, for example a lower flange. The lower connection element may be formed for example in such a way that it is connectable to a support member, preferably in interlocking and/or force-locked fashion. The connection profile may have an upper profile element, which is connectable to the transition piece, and a lower insert. An insert recess may be formed on an underside of the profile element and may correspond at least in some regions to an outer contour of the insert, in such a way that the insert may be connected in interlocking and/or integrally bonded fashion to the upper profile element. The insert may be connected to the upper profile element for example via one or more welded connections, preferably at least in some regions along the insert recess. The insert is typically connectable to a lower tower portion, preferably releasably, at its underside. A releasable connection, for example a screw connection, has the advantage that the transition piece and the connection profiles may be transported independently of one another and may be relatively easily assembled at a place of installation. A cross-section of the insert may preferably correspond to a cross-section of the support members. For example, a continuous force flow may thus be achieved, since a force offset is substantially avoided. In particular, the lower tower portion may have a lattice structure which comprises at least three support members extending over the length of the lower tower portion. The form of the insert may preferably correspond to a form of an upper end of the support members in such a way that the insert on its underside may be fitted onto the upper end of the support members, onto or into the upper end. The insert and the support members may also be connectable by an integrally bonded connection, for example welding, an interlocking connection, for example by being fitted in or on, and/or a force-locked connection, for example be flange-mounting, screwing, riveting, or the like. In addition, or alternatively, plug-in connections, screw connections, snap-action connections, adhesively bonded connections, or welded connections may be used. The insert and the support members may additionally or alternatively be connectable by means of thrust cleats. A support member may have, for example, a square profile with an edge length of 800 mm and a wall thickness of 25 mm. Each support member preferably has, in a cross-section perpendicular to a support member longitudinal axis, a lateral extent of at least 400 mm. A support member wall thickness is typically at least 10 mm, preferably at least 20 mm, and/or at most 60 mm. Of course, support members having other profile forms, for example U-profiles, rectangular or round profiles, may also be used.

The insert may have the task of ensuring a continuous transition from the profile element to the support member of the lattice structure located underneath. The insert preferably has the dimensions of the support attached below.

The connection profiles may have a cross-section that changes along the extent of the connection profiles, preferably continuously. It may be provided that a cross-section size and/or a cross-section shape change along the extent of the connection profile. In a cross-section, a connection profile in one specific embodiment has a triangular shape, widening upwardly. The upper triangle edge may be convex in this case. The lower tip of the triangle may be rounded, preferably concavely rounded. The side edges of the triangle may be of equal length or may have different lengths. The upper, preferably convex edge in a lateral extent may be longer than the lateral edges. The connection profiles may have a quadrangular or polygonal form in a cross-section. The form preferably widens towards the top in a cross-section. Quadrangular or polygonal cross-section forms may also have concave and/or convex regions. The connection profiles may be formed as a welded construction. The connection profiles may have welded-together wall panels with a wall thickness of at least 10 mm and/or at most 60 mm. The wall panels of a connection profile may have different wall thicknesses. A cross-sectional area of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, preferably decreases from top to bottom along this longitudinal axis. This has the advantage that a force flow may be optimized and at the same time only as much material as is necessary is used. This may lead to material savings and thus to cost savings. The connection profiles typically have a length along their extent of at least 1 m, preferably at least 8 m and/or at most 12 m. In particular for offshore applications, the connection profiles may also have a length along their extent of more than 12 m.

At least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have a convexly shaped outer contour at least in some regions. A force flow from the upper tower portion, via the transition piece, into the lower tower portion may thus be improved. Material may then be saved on account of such a force flow optimization.

At least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have a concavely shaped outer contour at least in some regions. A force flow from the upper tower portion, via the transition piece, into the lower tower portion may thus be improved. Stress peaks may be avoided by such an optimization of the force flow, and material may be saved.

The at least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have both a concavely shaped outer contour at least in some regions and a convexly shaped outer contour at least in some regions. Stress peaks may also be avoided by concavely curved forms.

The wall of the connection profile may be flat or curved once or more. A multiple curvature of the connection profiles may be realized in particular by a first curvature, for example by a design of the connection profiles that is concave and/or convex along the longitudinal axis, in combination with a curvature perpendicular to the longitudinal axis of the connection profiles.

In order to save material, the connection profiles may preferably be hollow, at least in some sections.

In order to save material, the walls of the connection profiles may be provided with recesses. The recesses may, for example, be covered with thin-walled sheets in order to protect the interior of the connection profiles from weather exposure. The connection profiles may be configured to be braced sheet metal constructions in order to reduce the sheet thickness of the profile elements.

In particular in the case of an offshore application of the transition piece, the connection profiles may be formed integrally with the transition piece. The connection profiles, for example, may be welded to the transition piece instead of, or in addition to flange connections.

Exemplary embodiments will be explained in greater detail below with reference to the drawings.

In the drawings:

FIG. 1 shows a transition piece in a perspective view;

FIG. 2 shows the transition piece in a side view in an xz plane;

FIG. 3 shows the transition piece in a plan view in an xy plane;

FIG. 4 shows the transition piece connected to an upper tower portion and to connection profiles, which in turn are connected to a lower tower portion;

FIG. 5a-c shows one of the connection profiles in three difference views;

FIG. 5d exploded view: connection profile, insert, and support member;

FIG. 6 shows the transition piece connected to four connection profiles;

FIG. 7 shows an upper tower portion, which is connected by means of the transition piece and the connection profiles to a lower tower portion;

FIG. 8 shows a schematic view of a cross-section along the hollow structure longitudinal axis;

FIG. 9 shows a detailed view of a connection between the connection profile and the lower tower portion and/or the transition piece;

FIG. 10 shows a perspective view of a connection region between a connection profile and a support member,

FIG. 11 shows a transition piece in a perspective view;

FIG. 12 shows the transition piece of FIG. 17 in a side view in an xz plane;

FIG. 13 shows the transition piece of FIGS. 17 and 18 in a plan view in an xy plane;

FIG. 14 shows the transition piece of FIGS. 17 to 19 in a view from below in an xy plane;

FIG. 15 shows the transition piece of FIGS. 17 to 21 with connection profiles in a side view;

FIG. 16 shows the transition piece of FIGS. 17 to 20 with connection profiles in a plan view;

FIG. 17 shows a schematic drawing of a transition piece connected to an upper tower portion and, via connection profiles, to a lower tower portion.

In FIG. 1, a transition piece 1 for connection of an upper tower portion 2 to a lower tower portion 5 via connection profiles 8 is shown. The transition piece 1 has an inner lateral surface 3, which widens upwardly in the form of a frustum of a cone, here in the z direction. The frustoconical inner lateral surface of the transition piece encloses an angle of 24° with a hollow structure longitudinal axis K. The inner lateral surface 3 has a smooth surface. In the shown example a hollow cone frustum, that of the inner lateral surface 3, has a wall thickness of 40 mm. At an upper portion of the transition piece 1, the transition piece 1 has an upper connection element 6. Here, the upper connection element 6 is formed as a ring flange via which an upper tubular tower portion is connectable to the transition piece 1, in particular by screwing and/or welding. The transition piece 1 is rotationally symmetrical about a hollow structure longitudinal axis K. The transition piece 1 also has four outer connection faces 7 arranged on an outer side 4 rotationally symmetrically about the hollow structure longitudinal axis K. The connection faces 7 protrude from the outer side 4. The connection faces 7 preferably extend practically over the entire height of the transition piece 1. The connection faces 7 may form a flange which extends substantially from an upper end of the transition piece 1 to a lower end of the transition piece 1. The connection faces 7 may be connected to corresponding bearing faces of a connection profile 8 (see FIGS. 5a-5c ). To this end, the connection profiles 8 may be screwed on and/or welded on, for example to the transition piece 1.

The connection faces 7 are, at least within a vertical projection of the connection profile longitudinal axis (L), arranged entirely below the connection element 6 and oriented in the force flow direction. This allows for a relatively simple force flow from the upper, tubular tower portion 2 to the support members 13.

The transition piece has its maximum lateral extent on an upper side. The lateral extent of the transition piece decreases from the upper side to the lower side. The outer side 4 of the transition piece 1 has elongate shapings 9 between the connection faces 7. In the shown example the shapings 9 extend from an upper edge of the transition piece 1 to a lower edge of the transition piece 1. In other embodiments the shapings may also extend only in some regions from an upper edge to a lower edge of the transition piece. The shapings 9 have a smooth inner face without edges or protrusions, such that stress peaks caused by notch stresses may be substantially avoided or reduced. The shown shapings 9 are curved inwardly (concavely) in the direction of the hollow structure longitudinal axis K. The form of the shown shaping 9 in FIG. 1, in a cross-section perpendicularly to the hollow structure longitudinal axis K, in this case may be elliptical or circular for example, at least in some regions. The outer contour of the transition piece in a cross-section perpendicular to the hollow structure longitudinal axis K may also describe a parabolic form in the region of the shaping.

The transition piece may consist, for example, of steel (for example structural steel S355), cast steel (for example nodular cast iron), reinforced concrete, fiber-plastics composite, or may contain combinations thereof. The transition piece is typically manufactured from steel. To this end, individual parts are usually cut to size, shaped, and joined together. The individual parts are typically joined together by welding; alternative possible joining methods, however, include screwing, riveting and adhesive bonding, for example.

The transition piece 1 in FIG. 1 has a maximum lateral extent A of 4.8 m. The height H of the transition piece 1 is 3.5 m. The connection face 7 protrudes with a collar height h of 20 cm relative to a framed outer side 4′ of the transition piece. In this case, the framed outer side 4′ is the outer side of the transition piece that is framed by the protruding connection faces 7. The framed outer side 4′ may have, in particular, the form of a region of an outer lateral surface of a cone frustum that widens towards the top. The framed outer side 4′, for example, in this case may constitute regions of an outer lateral surface of a cone frustum that comprises the inner lateral surface 3. In the region of the framed outer sides 4′, the cone frustrum has a wall thickness of 40 mm.

FIG. 2 shows a side view of the transition piece 1 of FIG. 1 in the xz plane. The connection faces 7, in FIG. 2, lie in a plane that is inclined relative to the xz plane and that encloses an angle α with the z axis. The connection faces 7 have a concavely rounded groove 7′ at an upper edge, and have a concavely rounded groove 7″ at a lower edge. The framed outer face 4′ is framed by the protruding connection faces 7.

FIG. 3 shows a plan view of the transition piece from above in an xy plane. Here, the inner lateral surface 3 is clearly visible. The cone frustum comprised by the inner lateral surface 3 has an opening 3′ at a lower end. The form of the opening 3′ corresponds here substantially to the lower circular base area of the cone frustum. A radius r of this circular opening 3′ corresponds in the shown example to a radius r′ of the four shapings 9. In other embodiments the radius r may be different from the radius r′ of the concavely rounded groove.

FIG. 4 shows a detail of a hybrid tower with an upper tubular tower portion 2, the transition piece 1, connection profiles 8, and a lower, lattice-like tower portion 5. The upper tower portion 2 is connected here to the transition piece 1 via the upper connection element 6, formed here as a ring flange, by means of screws. Furthermore, the transition piece 1, in particular with use of the transition piece 1 in a tower that is used in the offshore sector, may be connected at the connection faces 7 to the connection profiles 8 by welded connections. The connection profiles 8 are in turn connected at an underside to the lower tower portion 5. The connection profiles 8 and the connection of the connection profiles 8 to the lower tower portion 5 will be explained in greater detail in particular in the following drawings.

FIGS. 5a to 5c show a connection profile 8 from different perspectives. FIG. 5a shows the connection profile in a perspective side view. FIG. 5b shows the connection profile 8 in a view from below; FIG. 5c shows the connection profile 8 in a view from above. The connection profile comprises a profile element 11 and an insert 10. The profile element 11 has an insert recess 12 that is insertable into the insert 10. To this end, the insert recess 12 has a shape that corresponds to the outer contour of the insert 10 in a manner such that the insert 10 can be inserted into the insert recess with an accurate fit. The insert 10 is additionally connected to the insert recess 12 by means of welded connections and/or screw connections. In one embodiment, the profile elements 11 may, entirely or in part, also be formed as a supporting structure formed of rods. The connection profile 8 is preferably hollow. In particular in the plan view of FIG. 5c , it is clear that the connection profile 8, here in particular the profile element 11, of the shown exemplary embodiment comprises a curved wall 11′, in particular a wall curved convexly about a longitudinal axis L. The profile element 11, on the side opposite the convexly curved wall 11′, also comprises a concavely curved wall 11″, that is to say a concavely curved groove. The profile element 11, however, may also have side edges which are not curved, as may be seen for example in FIG. 5a . The profile element 11 may also be curved along the longitudinal axis L, and therefore may have single-curved and also double-curved walls. A cross-section of the connection profile 8 perpendicular to the longitudinal axis L may change continuously along its extent. A cross-sectional area of the connection profile 8 perpendicular to the longitudinal axis L typically decreases from top to bottom. Material may thus be saved since this is arranged depending on the effective loading. In this case, for example wind forces which act on an upper end of the upper tower portion are passed from the upper tower portion, through the transition piece 1, through the connection profiles 8, into the lower tower portion 5 and onwards into a foundation. The insert 10, as mentioned above, is preferably welded to the connection profile 8 at a contour of the insert 10′ facing the profile element 11. At an underside 10″ of the insert, the insert typically has an opening into which a support member of a lower, typically lattice-like tower portion can be inserted. A support member may preferably thus be connected to the insert in interlocking and/or integrally bonded fashion. It is additionally advantageous to releasably connect the support member to the insert by a flange connection, in particular by screwed flanges. In addition, or alternatively, plug-in connections, screw connections, snap-action connections, adhesively bonded connections, or welded connections may be used. FIG. 5d shows the connection profile 8, which comprises the upper profile element 11 and the insert 10, and the support member 13 in an exploded view. The insert recess 12 corresponds to the contour 10′ of the insert 10 facing the connection profile 8. The underside 10″ of the insert 10 is connectable to the support member 13. The insert 10, to this end, has an L-flange on its underside 10″, which L-flange corresponds to a support member flange 13′. A connection of this kind is described in greater detail in FIG. 9.

FIG. 6 shows a perspective view of the transition piece with four connection profiles 8. In the shown example, four connection profiles are arranged rotationally symmetrically about the hollow structure longitudinal axis K. In another exemplary embodiment, only three or more than four connection profiles 8 may also be arranged about the cone frustum axis K. The number of connection profiles 8 depends on the lower tower portion 5 and the number of support members 13 used there. FIG. 7 shows a lower tower portion 5 which has four support members 13. The fourth support member is hidden in the view shown in FIG. 7 by the support member 13′. The number of the support members 13 and the number of the connection profiles 8 always match, since each connection profile 8, as described above, is connected to a support member 13. A longitudinal axis L of the connection profile 8, in the shown example, encloses an angle τ of 42° with the cone frustum axis K. In other embodiments, the angle τ may be at least 30°, preferably greater than 40° and/or smaller than 90°, preferably smaller than 70°.

FIG. 8 shows a schematic view of a cross-section along the hollow structure longitudinal axis K of a transition piece 1 which corresponds substantially to that in the previous drawings. Four connection profiles 8 are connected to the transition piece. Four outer connection faces 7 of the transition piece 1 are arranged on an outer side 4 of the transition piece substantially rotationally symmetrically about the hollow structure longitudinal axis K. The transition piece has four collars 14, which protrude on the outer side 4 of the transition piece 1. Each collar 14 has a closed form in this case and forms a frame-like flange. The connection face in this case forms a surface of the collar 14, or frame-like flange. The collars 14 are formed integrally with the transition piece 1. At each of the outer connection faces 7, the transition piece 1 is connectable to one each of the connection profiles 8 that are connectable to a lower tower portion 5. To this end, the connection profiles 8 have a flange 15, the form of which corresponds to the form of the collar 14. A surface of the flange 15 of the connection profile 8 is placed against the connection face 7 and is connected thereto, for example by means of welded connections (in particular in the case of towers that are used offshore) or screw connections (in particular in the case of towers that are used onshore). The connection profiles 8 also have a frame-like flange 16 on an upper side, the form of said flange corresponding to the collar 14 of the transition piece in such a way that the frame 16 of the connection profile 8 is interlockingly inserted into the collar 14 of the transition piece 1 and/or is integrally bonded.

FIG. 9 shows a detailed view of a connection between the lower tower portion 5, for example in the form of a supporting structure formed by rods, and the connection profile 8. FIG. 9 may also show a connection between the connection profile 8 and the transition piece 1. For the sake of clarity, the reference signs used in FIG. 9 correspond to those of a connection between the lower tower portion 5 and the connection profile 8. The detailed view is shown in a cross-section along a support member longitudinal axis TA. Here, the connection profile 8, at its lower end 8′, has an inwardly protruding L-flange 15′. The L-flange 15′ may be arranged for example at the lower end 10″ of the insert 10. The L-flange 15′ has a bearing face 15″, against which a corresponding flange 5′″ of the lower tower portion 5 rests. The flange 5′″ is arranged at an upper edge 5″ of the lower tower portion. Due to the L form of the L-flange 15′, the connection profile 8 is insertable into the lower tower portion 5. The L-flange 15′ corresponds to the flange 5′″ of the lower tower portion 5 in such a manner that the lower tower portion 5 is connectable to the connection profile 8 in interlocking and/or integrally bonded fashion. The L-flange 15′ and the flange 5′″ further have coaxial holes. A screw is inserted through the coaxially corresponding holes and is fixed by means of a nut. The lower tower portion 5 and the connection profile 8 are thus additionally connected frictionally. The detailed view D shows this connection in an enlarged view. A connection of this kind may also be provided between the transition piece 1 and the connection profile 8. The transition piece 1 may thus be connected to the connection profile interlockingly and frictionally. To this end, the connection profile 8, at its upper end, has an above-described L-flange 15′, and the connection faces 7 of the transition piece 1 form a corresponding flange, which corresponds substantially to the flange 5′″ of the above description.

FIG. 10 shows, in a perspective view, a lower region of a connection profile 8, which is connected to a support member 13 via a flange connection. The shown connection profile 8 does not have an insert 10, but in another embodiment could also be formed having an insert 10. The shown connection profile 8, at a lower end 8′, has a flange in the form of a baseplate. This flange corresponds to a support member flange 13′. The flange of the connection profile 8 rests flat on the support member flange 13′. The flanges, for example, may be connected by means of screw connections.

FIG. 11 shows an alternative transition piece 1 in a perspective view. The transition piece 1 has an upper connection element 6 in the form of ring flange. The transition piece further comprises a hollow structure which tapers towards the bottom, with an outer lateral surface 3″ which widens towards the top. The inner lateral surface 3 also widens towards the top. The upper base areas of the outer and the inner lateral surfaces are configured to be circular. The lower base area 3′″ of the outer lateral surface has a triangular shape. The lower base area 3′″ of the inner lateral surface 3″″ also has a triangular shape. The hollow structure 1′ is formed by three sheets which are welded to one another at the edges 23 a, 23 b, 23 c. The sheets are each rounded in a manner such that a transition from the lower triangular shape to the upper circular shape is realized.

The outer lateral surface thus transitions/is reshaped from a lower base area in the shape of a polygon to a circle (positioned at the top). This construction (in this instance a single-layer shell) allows for a comparatively simple force flow from a connection face 6 to connection profiles 8. This also allows for a variable reaction to the number of support members 13 and connection profiles 8 and the amount of 3D-shaped sheets in the connection profiles 8 can be reduced.

FIG. 12 shows the transition piece of FIG. 11 in a side view in an xz plane, FIG. 13 shows the transition piece of FIGS. 11 and 12 in a plan view in the xy plane. The triangular shape of the lower base area of the inner lateral surface is easily visible in the plan view. The transition piece further has an inspection opening 3′.

FIG. 14 shows the transition piece of the previous figures in a view from the bottom, such that the outer lateral surface 3″ is easily visible. The triangular shape of the base area 3′″ of the outer lateral surface 3″ and the inspection opening 3′ are also easily visible. Die outer lateral surface has a circular upper base area. The sheets of the hollow structure are bent three-dimensionally and adjoin one another in a manner such that the outer lateral surface widens towards the top and describes, in part, a smooth transition from a polygonal base area towards a circular base area at the top.

The other features described above, in particular with regard to the transition piece of FIGS. 1 to 4, may be combined with the transition piece of FIGS. 11 to 16.

FIG. 15 shows, in a side view, the transition piece of FIGS. 11 to 14, wherein connection profiles are connected to the transition piece. FIG. 16 shows the transition piece of FIGS. 11 to 15 with assembled connection profiles in a plan view. The connection profiles may, for example, be welded and/or screwed to the transition piece. A connection via adhesive bonding is also conceivable. The connection profiles of FIGS. 15 and 16 substantially correspond to the those of the figures described above. The connection profiles 8 have, inter alia, a convexly curved wall 11′ like the connection profiles of FIG. 5 and are configured to be hollow. Moreover, a cross section decreases from the top toward the bottom along the connection profile longitudinal axis L. However, the wall 11″ across from the wall 11′ is not curved concavely but configured to be flat, as opposed to the walls of the connection profiles of the figures above. The connection profiles 8 further have side panels with recesses in order to save material and to reduce the weight of the connection profiles 8. In order to reduce the sheet thickness of the profile elements, the connection profiles 8 may be configured to be braced sheet metal constructions.

FIG. 17 shows a schematic view of a transition piece 1 according to the embodiments above, which transition piece is connected to an upper tubular tower portion 2 via the upper connection element 6. The transition piece 1 is connected to support members 13 of a lower, lattice-like tower portion via connection profiles 8.

Due to its topology, the transition piece allows for a merging of the lower edge of the upper tubular tower portion 2, the upper side of the connection profile 8, the upper side of an outer lateral surface of the hollow structure and the upper connection element 6 at an upper panel edge S1 without significant offset. The transition piece further allows for merging of the lower edge of the connection profile 8 with the lower edge of the outer lateral surface of the hollow structure at a lower panel edge S2 without significant offset.

The application further comprises the following aspects:

-   1. A transition piece (1) to connect an upper tubular tower portion     (2) with connection profiles (8),     -   wherein the transition piece (1) comprises         -   an upper connection element (6) to connect the transition             piece (1) to the upper tower portion (2) and         -   has an inner lateral surface (3) widening upwardly in the             form of a frustum of a cone and         -   has at least three outer connection faces (7), which are             arranged on an outer side (4) of the transition piece (1)             substantially rotationally symmetrically about a cone             frustum longitudinal axis and at which the transition piece             (1) is connected to one each connection profiles (8)             connected to a lower tower portion (5). -   2. The transition piece according to aspect 1, characterized in that     the upper connection element (6) is a flange, preferably a ring     flange. -   3. The transition piece (1) according to aspect 1 or 2,     characterized in that the connection faces (7) protrude at the outer     side (4). -   4. The transition piece (1) according to any one of the preceding     aspects, characterized in that the outer side (4) of the transition     piece (1) has elongate shapings (9) between the connection faces     (7), which shapings preferably extend from a top side of the     transition piece to an underside of the transition piece. -   5. The transition piece (1) according to any one of the preceding     aspects, characterized in that the transition piece is formed     integrally. -   6. The transition piece (1) according to any one of the preceding     aspects, characterized in that the transition piece (1) has, along     its longitudinal axis, a total height of at least 50% of a diameter     of the upper tower portion (2) at a lower edge of the upper tower     portion (2), preferably at least 80% of the diameter of the upper     tower portion (2) at a lower edge of the upper tower portion (2),     and/or at most 150% of the diameter of the upper tower portion (2)     at a lower edge of the upper tower portion (2). -   7. The transition piece (1) according to any one of the preceding     aspects, characterized in that the transition piece (1) has,     perpendicular to the longitudinal axis, a lateral extent of at least     0% of a diameter of the upper tower portion (2) at a lower edge of     the upper tower portion (2), preferably at least 105% of the     diameter of the upper tower portion (2) at a lower edge of the upper     tower portion (2), and/or at most 200% of the diameter of the upper     tower portion (2) at a lower edge of the upper tower portion (2),     wherein a maximum lateral extent is preferably configured to be at     an upper edge of the transition piece. -   8. The transition piece (1) according to any one of the preceding     aspects, characterized in that the transition piece is formed, at     least in part, as a supporting structure in the form of a shell. -   9. A connection profile (8) to connect a transition piece (1) with a     lower tower portion (5) wherein the connection profile (8) comprises     -   an upper flange corresponding to the connection faces (7) of a         transition piece in such a manner that the connection profile         (8) may be flange-mounted to the transition piece, and     -   a lower connection element to connect, preferably frictionally,         a connection profile (8) with a support member of a lower tower         portion (5). -   10. The connection profile (8) according to aspect 9, characterized     in that the connection profile (8) comprises an upper profile     element (11) that is connectable to the transition piece (1), and a     lower insert (10) and that an insert recess (12) is formed at a     lower side of the profile element (11), which at least in part     corresponds to the outer contour of the insert (10) in such a manner     that the insert (10) is connected to the upper profile element 11 in     interlocking and/or integrally bonded fashion. -   11. The connection profile (8) according to aspect 9 or 10,     characterized in that a cross-section of the connection profile (8)     changes continuously along an elongate extent along a longitudinal     axis (L) of the connection profile (8). -   12. The connection profile (8) according to aspect 9, 10, or 11,     characterized in that the insert (10) is connected to the profile     element (11) at least in part along the insert recess (12) by a     welded connection. -   13. The connection profile (8) according to any one of the aspects 9     to 12, characterized in that a cross-sectional area of the     connection profile (8) in the cross-section perpendicular to the     longitudinal axis (L) of the connection profile (8) decreases along     this longitudinal axis (L) from top to bottom. -   14. The connection profile (8) according to any one of the aspects 9     to 13, characterized in that at least one wall of the connection     profile (8), in a cross-section perpendicular to a longitudinal     axis (L) of the connection profile (8), has a convexly shaped outer     contour at least in some regions. -   15. The connection profile (8) according to any one of the aspects 9     to 14, characterized in that at least one wall of the connection     profile (8), in a cross-section perpendicular to a longitudinal     axis (L) of the connection profile (8), has a concavely shaped outer     contour at least in some regions. -   16. The connection profile (8) according to any one of the aspects 9     to 15, characterized in that a wall of the connection profile (8) is     flat or curved once or more. -   17. Connection profile (8) according to aspects 9 to 16,     characterized in that the connection profile (8) is hollow, at least     in some sections. -   18. The connection profile (8) according to any one of the aspects 9     to 17, characterized in that the insert (10) is removably     connectable to a lower tower portion, preferably via a flange     connection.

LIST OF REFERENCE SIGNS

-   1 transition piece -   1′ hollow structure -   2 upper tubular tower portion -   3 inner lateral surface -   3′ opening -   outer lateral surface -   3′″ lower base area of the outer lateral surface -   3″″ lower base area of the inner lateral surface -   4 outer side -   4′ framed outer side -   5 lower lattice-like tower portion -   5″ upper edge of the lower tower portion -   5′″ flange at the upper edge of the lower tower portion -   6 upper connection element -   7 connection face -   7′ concavely rounded groove at upper edge -   7″ concavely rounded groove at lower edge -   8 connection profile -   8′ lower end of the connection profile -   9 elongate recess -   10 insert -   10′ upper side of the insert -   10″ underside of the insert -   11 profile element -   11′ wall -   12 insert recess -   13 support member -   13′ support member flange -   14 collar -   15″ flange -   15′ L-flange -   15″ bearing face of the L-flange -   16 frame-like flange -   23 a, b, c edges -   A lateral extent of the transition piece -   H height of the transition piece -   K hollow structure longitudinal axis -   L connection profile longitudinal axis -   TA support member longitudinal axis -   r radius of the opening -   r radius of the elongate recess -   α angle between connection faces and hollow structure longitudinal     axis -   τ angle between connection adapter longitudinal axis and hollow     structure longitudinal axis -   S1 upper panel edge -   S2 lower panel edge 

1-21. (canceled)
 22. A transition piece to connect an upper tubular tower portion with connection profiles, wherein the transition piece comprises an upper connection element to connect the transition piece to the upper tower portion and a hollow structure which tapers towards the bottom, comprising a polygonal lower base area and a circular upper base area or a polygonal upper base area, wherein the polygonal lower base area has fewer corners than the polygonal upper base area.
 23. The transition piece according to claim 22, wherein the lower base area is configured to be triangular, round, or polygonal, wherein the number of corners preferably corresponds to the number of connection profiles.
 24. The transition piece according to claim 23, wherein a largest lateral extent of the transition piece is at an upper side of the transition piece in the region of the upper connection element.
 25. The transition piece according to claim 24, wherein the transition piece comprises at least three connection faces arranged at an outer side of the transition piece, on which the transition piece is connectable with at least three connection profiles.
 26. The transition piece according to claim 22, wherein the connection faces are, at least within a vertical projection of the connection profile longitudinal axis, arranged entirely below the connection element.
 27. The transition piece according to claim 22, wherein the hollow structure has an inner lateral surface widening toward the top, wherein the inner lateral surface has a polygonal lower base area and a circular upper base area.
 28. The transition piece according to claim 22, wherein the hollow structure has an inner lateral surface widening toward the top, wherein the inner lateral surface has a polygonal lower base area and a polygonal upper base area, wherein the polygonal lower base area has at least the same number of corners or fewer corners than the polygonal upper base area.
 29. The transition piece according to claim 22, wherein the transition piece has, along its longitudinal axis, a total height of at least 50% of a diameter of the upper tower portion at a lower edge of the upper tower portion, including at least 80% of the diameter of the upper tower portion at a lower edge of the upper tower portion, and/or at most 150% of the diameter of the upper tower portion at a lower edge of the upper tower portion.
 30. The transition piece according to claim 22, wherein the transition piece has, perpendicular to the longitudinal axis, a lateral extent of at least 0% of a diameter of the upper tower portion at a lower edge of the upper tower portion, including at least 105% of the diameter of the upper tower portion at a lower edge of the upper tower portion, and/or at most 200% of the diameter of the upper tower portion at a lower edge of the upper tower portion, wherein a maximum lateral extent is configured to be at an upper edge of the transition piece.
 31. The transition piece according to claim 22, wherein the transition piece is formed, at least in part, as a supporting structure in the form of a shell.
 32. A connection profile to connect a transition piece with a lower tower portion wherein the connection profile comprises an upper flange corresponding to the connection faces of a transition piece in such a manner that the connection profile may be flange-mounted to the transition piece, and a lower connection element to connect, preferably frictionally, a connection profile with a support member of a lower tower portion.
 33. The connection profile according to claim 32, wherein the connection profile comprises an upper profile element that is connectable to the transition piece, and a lower insert and that an insert recess is formed at a lower side of the profile element, which at least in part corresponds to the outer contour of the insert in such a manner that the insert is connected to the upper profile element in interlocking and/or integrally bonded fashion.
 34. The connection profile according to claim 33, wherein a cross-section of the connection profile changes continuously along an elongate extent along a longitudinal axis of the connection profile.
 35. The connection profile according to claim 34, wherein the insert is connected to the profile element at least in part along the insert recess by a weld connection.
 36. The connection profile according to claim 35, wherein a cross-sectional area of the connection profile in the cross-section perpendicular to the longitudinal axis of the connection profile decreases along this longitudinal axis from top to bottom.
 37. The connection profile according to claim 35, wherein at least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, has a convexly shaped outer contour at least in some regions.
 38. The connection profile according to claim 37, wherein at least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, has a concavely shaped outer contour at least in some regions.
 39. The connection profile according to claim 38, wherein a wall of the connection profile is flat or curved once or more.
 40. The connection profile according to claim 39, wherein the connection profile is hollow, at least in some sections.
 41. The connection profile according to claim 32, wherein the insert is removably connectable to a lower tower section, including via a flange connection.
 42. The connection profile according to claim 32, wherein at least one wall of the connection profile comprises a side panel with a recess, including with an elongate recess. 